A voltage regulator is designed to automatically ‘regulate’ voltage level. It basically steps down the input voltage to the desired level and keeps that in that same level…
INTRODUCTION Almost all basic household electronic circuits need an unregulated AC to be converted to constant DC, in order to operate the electronic device. All devices will have…
Phase Locked Loops (PLL) Introduction to PLL The concept of Phase Locked Loops (PLL) first emerged in the early 1930’s.But the technology was not developed as it now,…
Introduction to Operational Amplifiers In this post, the basics of an operational amplifier (generally abbreviated as op-amp) will be analysed along with its block diagram, basic structure, symbol,…
Programmable UJT (PUT). Programmable unijunction transistor or PUT is a close relative of the thyristor family. Its has a four layered construction just like the thyristors and have…
UJT relaxation oscillator UJT relaxation oscillator is a type of RC ( resistor-capacitor) oscillator where the active element is a UJT (uni-junction transistor). UJT is an excellent switch…
How to trigger an SCR using UJT ? One common application of the uni junction transistor is the triggering of the other devices such as the SCR, triac…
Current ratings of an SCR The current carrying capability of an SCR is solely determined by the junction temperature. Except in case of surge currents, in no other…
SCR Voltage Ratings (i) Breakover Voltage. The minimum forward voltage, when the gate is open, at which SCR starts conducting heavily (that is turned-on) is called the breakover…
SCR-Ratings and Specifications The performance of an SCR is affected by the junction temperature, because of change in carrier densities in the four layers and the junction temperature…
Turning-off Methods of an SCR As already mentioned in previous blog post, once the SCR is fired, it remains on even when triggering pulse is removed. This ability…
How to turn ON an SCR ? As mentioned earlier, the SCR can be switched on either by increasing the forward voltage beyond forward break over voltage VFB0…
Turn-on and turn-off characteristics of an SCR are called the dynamic characteristics of the SCR. (a) Turn-On Characteristic. The turn-on time characteristic shows the variation of current and voltage…
As already mentioned, the SCR is a four-layer device with three terminals, namely, the anode, the cathode and the gate. When the anode is made positive with respect…
How an SCR works?-Principle of Operation SCR Working Principle The SCR is a four-layer, three-junction and a three-terminal device and is shown in fig.a. The end P-region is…
Introduction to SCR-Silicon Controlled Rectifier As the terminology indicates, the SCR is a controlled rectifier constructed of a silicon semiconductor material with a third terminal for control purposes.…
Comparison of Thyristor and Transistor As already mentioned, transistors and thyristors are both semiconductor devices. They are now widely employed in switching operations because of their numerous advantages…
Comparison between Thyristors and Thyratrons Before the discovery of thyristors, thyratrons were used for industrial control, but now they have been replaced by the thyristors because of the…
Thyristor Family-Types of Thyristors The P-N-P-N devices with zero, one or two gates constitute the basic thyristor. But today the thyristor family includes other similar multilayer devices also.…
General Introduction to Thyristors and its Applications Thyristor is the general name given to a family of semiconductor devices having four layers with a control mechanism, although this…
JFETs and MOSFETs are quite similar in their operating principles and in their electrical characteristics. However, they differ in some aspects, as detailed below : JFETs can only…
Introduction to IGBT-Insulated Gate Bipolar Transistors Insulated gate bipolar transistor (IGBT) is a new high conductance MOS gate-controlled power switch. The fabrication process is similar to that of…
MOSFET requires very careful handling particularly when out of circuit. In circuit a MOSFET is as rugged as any other solid-state device of similar construction and size. MOSFETs…
All MOS devices have insulated gates that are subject to voltage breakdown. For instance the gate oxide for Motorola CMOS devices is about 900 A thick and breaks down…
Introduction to CMOS-Complimentary Metal Oxide Semiconductor FET’s Complementary metal oxide semi-conductor devices are chips in which both P-channel and N-channel enhancement MOSFETs are connected in push-pull arrangement. The basic…